Fall Drawdown to Begin

Yesterday, our dam owner called the MPA President to inform all of you that the fall drawdown of the water level has begun. The gates have been opened to bring the water down to the fall rule curve level. Hurricane Hanna earlier this month did bring the level up above their curve, and yes I know, perhaps the highest our water has been this summer. But it is time to bring it back down.

Don’t panic! I know many of us have been longing for higher water all summer -especially those of us down the channel, in the coves and on the shallower Sutton side – but let’s remember it is the end of the season. The water has to be brought down before November. Brought down before the critters overwinter in mud, before the lake begins to freeze, and brought down for the weed control.

Here’s a little outline/summary of the timing of lake-level drawdown for weed control from the Lycott Enviromental’s fact sheet. The drawdown reduces the number of weeds by leaving them exposed and/or freezing them. Those resistant to freezing can actually be pulled from the sediment when the ice layer is raised as the the water level is quickly brought up. This method was recommended to the MPA back in 1990 and again in 2003 by Lee Lyman of Lycott for us here on Manchaug:

~ Gradually begin the drawdown mid-September to early October taking the level “down at a rate of approximately one-to-two inches per day” to “allow certain aquatic organisms such as fresh water mussels, crayfish, turtles and amphibians to migrate to deeper portions of the water body to over-winter.”

~ The lowered water level should be maintained during November and December until there is a prolonged period (5-7 days) of temperatures below 15 degrees F.”

~ Refilling should begin in “early January regardless of the weather conditions.” This eliminates concerns of unsafe ice in March and ensures successful refill as “the water body should not be in a lowered condition during the spring and/or early summer, as terrestrial plants will flourish on the exposed sediment…”

MPA has worked with the dam caretaker since 1990 to fine tune the fall/winter drawdown so as to control the weeds without having to use herbicides. Yes, some years it didn’t happen or the weather wasn’t with us but on the whole it has been a cost free, effective method for Manchaug Pond. We are hoping the new rule curve effort will include the weed control program in its scope.